Preparation of mercaptans



Patented June 20, 1944 2351316: PREPARATION OF MTERCAPTANS Carl Max Hull, Chicago, 11]., aselgnor to Standard giucompany, 1 Chicago, a co poration of ana No Drawinl. Application February 16, 1942,

Sel'lal No. 431,081

16 Claims.

This invention relates to improvements in the preparation of mercaptans and more particularly to the preparation of aliphatic or cyclo aliphatic mercaptans.

or alicyclic-substituted alkyl. or alicyclic hydrocarbons having a --CH=CH grouping in a ring of 3 or more carbon atoms. Stated another way, I prefer to employ oleflnic compounds which The preparation or mercaptans by treating al- 5 would give primary and/or secondary mercapkyl halides with alkali hydrosulfides is well known tans by simple addition of H28 as H and -SI-I, to those versed in the art; however this method since in general, the primaryand secondary merquires a p r ty of St ps and produces a prodcaptans are more stable and hence recoverable uct which is a mixture of mercaptans and alcoin higher yields than are the tertiary mercaphols which are diiiicult to separate and results tans. However, the stability of tertiary mercapin low yields of mercaptans. It is also known to tans varies with the molecular weight, those of p p merc ptaus by r cting an olefin with lower molecular weight having the greater stahydrogen sulfide. latter method requires bility, and with the particular configuration of the use of catalysts, complicated pressure equipthe carbon skeleton. Therefore, mercaptans defiiii' .i ifisiitbie$133333? ilt? i 1% the 11 tii c ii e e ene er va ves suc as =C "R"' icilit is an (first o'fi the przeisent inventiion tofprowherle tihree at; more oflsthe substituent groups v e a me o prepa ng mercap ans mm are y rocar n radica are also within the oleflns which gives a high yield 01 mercaptans scope of the invention. and which reslulits in subsgiantially no additional Specific examples illustrative of the unsaturatby-pro ucts w ch are di cult to separate from ed hydrocarbons which can be used in accordance :he fissiged rrtiercarptags. Agott'fiei object 01 Lilia with the present invention are the following:

nve 10 s o pov ea e o o prepar g mercaptans from olefins which does not require Mono Olefins the use of catalysts and whichgives a high yield Ethylen CHFCH: of 'mercaptans, without the formation of unde- Propylene sirable lay-products. Mute CHQCHL'CH Other objects and advantages of the present omcmcrmam invention will become apparent from the fol- Gig-butane CH CH lowing description thereof. a

I have discovered that the foregoing objects Tranwbutene CHJCH can .be attained by the prepara i n of 'me c ponion tans by the process comprising the reaction. of H CH phosphorus pentasulfide with an unsaturated hydrocarbon and subsequent hydrolysis of the re- Methylpmpenfl CH suiting reaction product. The unsaturated hydrocarbons employed are taken from the general class of hydrocarbons containing one or more non-benzenoid double bonds, and preferably those l meme Cmcmcmclkcm having from 2 to about 12 carbon atoms in a 40 m omcmondmen, molecule. The term fim'saturated hydrocarbon P 116 as used herein and in the appended claims ineludes olefins, dien'es; polyenes, unsaturated ali- CH1 cyclic hydrocarbons, and derivatives of the above- A; mentioned classes of hydrocarbons having sub- H CH stituent groups which are substantially inert under the conditions of my process. For exam- Ali Dom ple, the unsaturated hydrocarbon may contain hydrocar one or more hydrocarbon substituents such as Methylcyc f cycloaliphatlc or aromatic groups. Other inert Q groups or atoms such as the halogens may 8150 HCH1 bepresent. Cyclopentadione While all 01' th above-mentioned unsaturated on=cn hydrocarbons and derivatives will react in my process to give mercaptans, I Prefer to employ unsatm'ated hydrocarbons having the type for- 0mm =9 oncmcm =cH R' lmothyl l-cyelohexeno Hem H, where R and R are radicals taken from the class including hydrogen, alkyl, aryl, aromaticco 11cm in In accordance with the present invention the phosphorus pentasulflde is added, preferably as a flne powder. to an excess of the rmsaturated hydrocarbon employed, for example about 1 mole of the phosphorus pen do and an amount exceeding about 2 moles of the unsaturated hydrocarbon by weight. If desired a suitable solvent such as benzene or a petroleum naphtha, preferably an olefin-free naphtha, may lfi employed. when such a solvent is used the reactants may be employed in the proportions of about 1 mole of phosphoruspentasulflde to about 2 moles of the unsaturated hydrocarbon. The mixture of phosphorus pentasulflde and unsaturated hydrocarbon is maintained with good agitation at about 100 1''. to 400" F. for about i to 30 hours depending on the temperature and the hydrocarbon used. The reaction may be suitably car-' ried out by refluxing in an inert gas which may be bubbled through the mixture to obtain better contact of the reactants. At the end of the heating period the mixture is flltered and the filtrate is freed of excess unsaturated hydrocarbon and any solvent, by distillation under reduced pressure or other suitable means. The residue remaining after the removal of the excess unsaturated hydrocarbon-and solvent (if any) is then'hydrolyzed by passing steam through the residue at a temperature of from about 200 F. to about 500 F. and preferably at about 250 F. to about 400 F. During the steam treatment the mercaptan if volatile is distilled together with a small amount of some lizhter and heavier products. treatment the distillate may be redistilled (under reduced pressure if desired) to obtain a constant boiling mercaptan fraction. If high molecular weight unsaturated hydrocarbons are employed the resulting mercaptans may he sepa'-' rated more eflectively from the undesired products by extraction with suitable non-polar solvents, such as a light naphtha of such boiling range that it can later be separated readily from the extract.

The reaction between phosphorus pentasulflde and the unsaturated compound may sometimes be accomplished more rapidly under pressurepreferably at a pressure suflicient to maintain the olefin in a liquid phase-particularly in the case of the more volatile unsaturated compounds. The use of pressure is particularly important when gaseous oleflns with low critical tempera tures such as, for example, ethylene are used. Pressures up to about 100 atmospheres or more maybe used.

The following specific example for the preparation of cyclohexyl mercaptan is intended to be illustrative of thepresent invention and not to be construed as a limitation thereof:

One part of phosphorus pentasuliide and two parts of cyclohexene by weight were placed in a flask and refluxed for 25 to 30 hours at about 180 F. while blowing nitrogen through the mixture. The reaction mixture was allowed to settle, and then decanted through a filter. The excess cyclohexene was removed in a pure state by distillation up to a temperature of about 300 F. in a stream of CO2, vacuum being employed to remove traces of cyclohexene, leaving an amber-color resin-like residue. The residue was then hydrolyzed by passing steam through the same at a temperature of 400 F. and the mercaptan along with a small amount of some lighter and heavier products distilled. A distillate Upon completion or the steam assures weighing 39% and a residue weighing 58% of the original charge were obtained. I

The distillate was then distilled through a packed column and the following fractions obtained:

' Refractive Fraction No. 1322; index Yield F. Per cent 1 113-200 1.451 c coo-s00 1.410 s a soc-3:2 1.4930 so 1. 5382 24 The following comparative data of fraction No. 3 and reported constants for cyclohexyl mercaptan establishes that fraction No. 3 is substantially pure cyclohexyl mercaptan.

In addition to the above data a solution of fraction No. 3 in sweet naphtha was titrated with copper solution and 25% mercaptan sulfur found, whereas the theoretical amount for cyclohexyl mercaptan is 27.6%.

While I have illustrated my invention with reference to the preparation of cyclohexyl mercaptan I do not wish to limit the invention there to, but contemplate as within the scope of my invention the production of other mercaptans by the hydrolysis of the reaction product of phosphorus pentasulflde and other unsaturated hrdrocarbons as hereinbeiore defined.

I claim:

1. The method of preparing mercaptans comprising hydrolyzing the reaction product of phosphorus pentasulflde and an unsaturated hydrocarbon.

2. The method of preparing mercaptans comprising hydroLvzing the reaction product of phosphorus pentasulflde and a hydrocarbon containing at least one olefinic double bond.

3. The method of preparing mercaptans comprising hydrolyzing the reaction product of phosphorus pentasulfide and a mono-olefin hydrocarbon.

4. The method of preparing mercaptans comprising hydrolyzing the reaction product of phosphorus pentasulfide and an unsaturated aiicyclic hydrocarbon.

5. The method of preparing mercaptans comprising hydrolyzing the reaction product of phosphorus pentasulflde and a polyene hydrocarbon.

6. The method prising hydrolyzing the reaction product oi phosphorus pentasulflde and cyclohexene.

'7. The method of preparing mercaptans comprising reacting about one mole' of phosphorus pentasulflde and about two moles of an unsaturated hydrocarbon, separating the unreacted reactants from the reaction product, hydrolyzing said reaction'product with steam at a temperature of from about 200 F. to about 500 F. and separating the mercaptan fraction from the hydrolyzed reaction product.

8. The method of preparing mercaptans comprising reacting about one mole of phosphorus of preparing mercaptans com-v pentasulfide and about two moles of an olefin hydrocarbon, separating the unreacted reactants i'rom the reaction product. hydrolyzing said reaction product with steam at a temperature of from about 200 F. to about 500 F. and separating the mercaptan fraction from the hydrolyzed reaction product.

9. The method of preparing mercaptans comprising reacting about one mole of phosphorus pentasulfide and about two moles of cyclohexene,

the unreacted reactants from the reaction product, hydrolyzing said reaction product with steam at a temperature of from about 200' I". to about 500' I". and separating the mercaptan fraction from the hydrolyzed reaction product.

10. The process of obtaining mercaptans comprising refluxing a mixture comprising about one mole oi phosphorus pentasulfide and an amount exceeding about two moles oi an unsaturated hydrocarbon at a temperature of from about 100 1''. to about 400 1''. while bubbling an inert gas through said mixture, filtering the reaction mixture, .separating the excess hydrocarbon irom the filtrate, hydrolyzing the reaction product bypassing steam therethrough at a temperature oi from about 2 F. to about 500 1''. and subsequently recovering the desired mercaptan fraction by distillation.

11. The process of obtaining mercaptans comprising refiuxing a mixture comprising about one mole oi phosphorus pentasulfide and anamount exceeding about two moles of an olefin hydrocarbon at a temperature or from about 100 F. to about 400' R, filtering the reaction mixture, separating the excess hydrocarbon from the filtrate, hydrolyzing the reaction product by passing steam therethrough at a temperature or from about 200' 1 to about 500 F. and subsequently recovering the desired mercaptan tracdistillation.

tion by 12. The process of obtaining mercaptans comrefi a mixture comprising about one prising uxing mole oi phosphorus pentasulilde and an amoimt exceeding about two alicyclic hydrocarbon about F. to about 400 F., filtering the reaction mixture, carbon from the tion product by a temperature of from about 200 F. to about 500 F. and subsequently recovering the desired mercaptan fraction by distillation.

13. The method of preparing cyclohexyl mercaptan comprising reacting a mixture comprising one part phosphorus pentasulfide and two parts cyclohexene, for about 25 to about 30 hours at a temperature of about F. by blowing nitrogen through the mixture, filtering-the reaction mixture, distilling the filtrate at a tem-- perature of about 300 F. to remove the excess cyclohexene. hydrolyzing the residue from said distillation by passing steam through the same at a temperature 01' about 400 F. to obtain a distillate containing cyclohexyl mercaptan and subsequentlydistilling said distillate to obtain the desired cyclohexyl mercaptan traction.

14. The method of preparing mercaptans comprisinghydrolyzing the reaction product of phosphorus pentasulfide and a hydrocarbon containing at least one non-benzenoid double bond.

15. The method described in claim 14 in which the hon contains from 2 to about 12 carbon atoms in the molecule.

16. The process of obtaining mercaptans comprising refluxing a mixture comprising about one mole of phosphorus pentasulfide, about two moles of an unsaturated hydrocarbon, and a solvent at a temperature oi from about 100 F.

separating the excess hydroiiltrate, hydrolyzing the reacto about 400 F., filtering the reaction product,

separating the excess hydrocarbon from the filtrate, hydrolyzing the reaction product by passing steam therethrough at a temperature of from about 200 F. to 500 F. and subsequently recovering the desired mercaptan fraction by distillation.

CARL MAX HULL.

passing steam therethrough at 

